Exercise and our immune system

We know it builds muscle and bone, and it’s good for our heart and brain, but exercise also seems to boost our immunity.

We’ve seen this in a recent English study on older recreational cyclists — 41 women and 84 men, aged 55 to 79. They were keen riders who’d kept it up as they’d grown older.

When I say ‘keen’, the women could ride 60kms in under 5.5 hours, and the men could do 100kms in under 6.5 hrs.

Actually, they were involved in two studies, and in both they were compared with two other groups — a sedentary group of similar age, and a group of young people aged 20-36 who didn’t do any regular, intense exercise.

The first study showed that when it came to reflexes, memory, balance and metabolism, the older cyclists were more like the 30-year-olds than their sedentary counterparts.

Their muscle tissue also resembled that of people 20 years younger.

It was the second study that focused on immunity. Here the cyclists were shown to have almost as many new T cells (a type of white blood cell that kills off infection and cancer) in their blood as the young people did.

They also had high levels of other immune cells that help to prevent autoimmune reactions, and of a hormone that protects the thymus gland against shrinkage. (The thymus sits between our lungs and is a key part of our lymphatic system.)

As it turns out, muscles are an important source of this hormone.

So physical activity seems to play an important role in immunity. And while you might not have much interest in knocking out 60 kms on a bike — or getting about in lycra — it’s likely that you don’t have to.

More research will probably confirm that following the guideline of 30 minutes a day five days a week makes a major difference.